BOB URZ wrote:

I have often wondered. Given a 24 hour advanced notice that an attack
was eminent in 72 hours or less, what would have been the outcome at
Pearl Harbor? Say on dec 6, Pearl was given intel that an attack would
come anytime in the next 72 hours.
....snipped...
It would make an interesting movie.....

BOB

Assumption:
- They really believed the warning and took it seriously.

They could have sortied all naval vessels out of Pearl Harbor and
dispersed them out to sea. Perhaps the individual ships would have been
more vulnerable (if they were found), but I don't know if the Japanese,
on finding Pearl empty, had the fuel or the interest in doing an open
ocean search or just going back.

However, because they concentrated on bombing the ships, the critical
repair, maintenance and logistics facilities and stores were left
virtually untouched. If they got to Pearl and found no ships, would they
have seriously hit those other facilities and caused even more damage
than they did?

We also could have had a serious CAP up and assumed the unknown
incomings on radar were hostile instead of just... unknown. What
difference would this have made? Unknown.

More importantly, on a strategic level, if we had known about the attack
in advance, would the US have reacted as strongly and been as committed
to the war? Morale is always a critical (but often overlooked) factor.
Without "a day that will live in infamy", what would have been the US's
reaction? Would we have been as committed?